Back to EveryPatent.com
United States Patent |
6,139,011
|
Huang
,   et al.
|
October 31, 2000
|
Jam clearance for printer path by manual operation
Abstract
A printer having a facility for manually directing a printing medium along
a printing medium path. The printer includes an external housing, a drive
roller arranged about an axis of rotation for feeding a printing medium
through a processing zone of the printer, a control member arranged about
an axis of rotation, and movable between a first axial position in which
the control member protrudes from said external housing so as to be
manually actuable, and a second axial position in which the control member
is retracted relative to the first axial position, and a coupling
mechanism selectively coupling the control member and the feed roller to
translate rotational movement of the control member into rotational
movement of the feed roller, said coupling mechanism being engaged when
the control member is in the first axial position and disengaged when the
control member is in the second axial position.
Inventors:
|
Huang; Pui Wen (Singapore, SG);
Yip; Kok Sam (Singapore, SG);
Chua; Ching Yong (Singapore, SG);
Wu; Seng Lim Richard (Singapore, SG)
|
Assignee:
|
Hewlett-Packard Company (Palo Alto, CA)
|
Appl. No.:
|
165021 |
Filed:
|
October 2, 1998 |
Current U.S. Class: |
271/274; 271/114; 271/273; 271/902 |
Intern'l Class: |
B65H 005/02 |
Field of Search: |
271/902,273,274,114
400/636,637,636.3,637.1
|
References Cited
U.S. Patent Documents
3682550 | Aug., 1972 | Samuels et al. | 271/56.
|
4247212 | Jan., 1981 | Wu | 400/556.
|
4529188 | Jul., 1985 | Sturnick | 271/114.
|
4900003 | Feb., 1990 | Hashimoto | 271/114.
|
4930916 | Jun., 1990 | Fujiwara | 400/636.
|
4976557 | Dec., 1990 | Uchikata | 400/565.
|
Primary Examiner: Walsh; Donald P.
Assistant Examiner: Schlak; Daniel K
Claims
What is claimed is:
1. A printer having a facility for manually directing a printing medium
along a printing medium path, the printer comprising:
an external housing;
a drive roller arranged about an axis of rotation for feeding a printing
medium through a processing zone of the printer;
a control member arranged about an axis of rotation, and movable between a
first axial position in which the control member protrudes from said
external housing so as to be manually actuable, and a second axial
position in which the control member is retracted relative to the first
axial position;
a linkage mechanism coupled to the control member, such that when the
control member is in the first axial position, the linkage mechanism stops
further feeding of individual media into the printer; and
a coupling mechanism selectively coupling the control member and the drive
roller to translate rotational movement of the control member into
rotational movement of the drive roller, said coupling mechanism being
engaged when the control member is in the first axial position and
disengaged when the control member is in the second axial position.
2. A printer as claimed in claim 1, wherein the control member is biased
towards the second axial position.
3. A printer as claimed in claim 1, wherein the control member is
substantially flush with the external housing in the second axial
position.
4. A printer as claimed in claim 1, wherein the control member comprises an
axial shaft with a manually actuable knob at a distal end thereof.
5. A printer as claimed in claim 4, wherein the knob includes a hinge
supporting a lever, which lever may be extended to aid movement of the
control member from the second axial position to the first axial position,
and to aid continuous manual rotation of the knob.
6. A printer as claimed in claim 4, wherein the printer further comprises;
A picking mechanism selectively coupled to the drive roller, for picking
individual sheets of media from a sheet media stack; and
wherein the linkage mechanism is coupled to the shaft of the control
member, such that when the control member is in the first axial position,
the linkage mechanism engages with the picking mechanism to disable
picking of further individual sheets.
7. A printer as claimed in claim 6, wherein the linkage member comprises a
shaft arranged in parallel with the control member shaft, and a pivotally
mounted lever attached to both the control member shaft and the linkage
member shaft, the lever translating axial movement of the control member
shaft in one direction into axial movement of the linkage mechanism shaft
in an opposite direction, whereby movement of the control member to the
first axial position causes movement of the linkage mechanism shaft in a
direction so as to engage with the picking mechanism to disable further
picking of further individual sheets.
8. A printer as claimed in claim 1, wherein the drive roller and the
control member are arranged about parallel axes of rotation.
9. A printer as claimed in claim 1, wherein the coupling mechanism
comprises a gear train having at least two gears which mesh with each
other when the control member is in the first axial position such that a
manual angular displacement of the control member causes a proportional
angular displacement of the drive roller.
10. A printer having a facility for manually directing a printing medium
along a printing medium path, the printer comprising:
a drive roller arranged about an axis of rotation for feeding a printing
medium through a processing zone of the printer;
a control member comprising an axial shaft with a manually actuable knob at
a distal end thereof, the control member arranged about an axis of
rotation, and movable between a first axial position and a second axial
position;
a coupling mechanism selectively coupling the control member and the feed
roller to translate rotational movement of the control member into
rotational movement of the feed roller, the coupling mechanism being
engaged when the control member is in the first axial position and
disengaged when the control member is in the second axial position;
a picking mechanism coupled to the drive roller, for picking individual
sheets of media from a sheet media stack; and
a linkage mechanism coupled to the shaft of the control member, such that
when the control member is in the first axial position, the linkage
mechanism engages with the picking mechanism to disable further picking of
sheets.
11. A printer as claimed in claim 10, wherein the linkage member comprises
a shaft arranged in parallel with the control member shaft, and a
pivotally mounted lever attached to both the control member shaft and the
linkage member shaft, the lever translating axial movement of the control
member shaft in one direction into axial movement of the linkage mechanism
shaft in an opposite direction, whereby movement of the control member to
the first axial position causes movement of the linkage mechanism shaft in
a direction to engage with the picking mechanism to disable further
picking of sheets.
Description
This invention relates to a printer having a facility for manually
directing a printing medium along a printing medium path. In particular,
the invention relates to a printer apparatus having an improved manual
paper jam removing capability. In the context of this invention, the term
printer is intended to include impact printers, laser printers, inkjet
printers, copiers, fax machines and other relevant image forming machines
employing printing medium paths.
BACKGROUND TO THE INVENTION
One type of image forming machine employing a printing medium path is a
"sheet-feed" printer. In a known "sheet-feed" printer, sheets of paper or
other printing media are pulled or picked from an input tray and fed
downstream into the print engine components where the desired image is
formed on each sheet. This operation is typically accomplished using a
series of motor driven rollers that have frictionally adherent surfaces.
The surface of the initial or pick roller rotates against the upper
surface of the top sheet in the stack to direct the top sheet along a
predetermined printing medium path. The sheet is advanced through an
infeed zone and is received by a drive roller which supplies the sheet
into a processing zone for printing. The sheet is then expelled through an
output zone or tray. This cycle is repeated for each sheet to be printed.
FIGS. 1a to 1c show a few of the components used in this type of printer.
A problem experienced with printers of this type is that the sheet being
fed may become subject to a disturbance somewhere along the printing
medium path. The disturbance is typically the result of a sheet having
imperfections or becoming skewed in the infeed zone. Usually, the part of
the sheet encountering the disturbance will be blocked, whilst the
remaining part will continue its progression along the printing medium
path by the action of the rollers. Accordingly, the sheet will build up
against the blockage until the rollers operating in the direction of the
blockage no longer adhere to the fed sheet. Consequently, the sheet will
become "jammed" in the printer mechanism as illustrated, for example, in
FIGS. 1d and 1e. This effect is known as a sheet or paper jam. Sheet or
paper jams can also occur in the other types of printers referred to above
which employ printing medium paths.
Although the frequency of paper jams in modern printers has generally
decreased, when this problem does occur the result can have a damaging
effect on the printer. The printer motor, for example, can over-heat as a
result of the increased load on the rollers. Also, in printers using ink,
the image forming components may deposit ink within the printer instead of
on the printing medium. In order to reduce the damaging effects of paper
jams, printers have been developed which can detect certain indicators of
a paper jam so that the operations of the printer are ceased as soon as
possible.
Once a paper jam has occurred the jammed paper will often end up
concertinaed in some form next to the drive roller as illustrated in FIG.
1d. Removal of the paper to clear the jam may then be performed manually
by grabbing one of the ends of the paper and pulling. However, this method
is undesirable since the paper may rip or unnecessary strain may be placed
on the motor as the drive roller is forced around too quickly.
A more suitable and commonly used method of removing a jammed sheet of
paper is to manually rotate the drive roller to direct the paper along the
printing medium path. This manual rotation may be enabled by a knob
located outside the printer housing which is attached to the drive roller.
The drive roller may be rotated either in a forwards direction to direct
the jammed sheet towards the output zone or in a reverse direction to
direct the jammed sheet towards the infeed zone. The choice of direction
is arbitrary and both directions are generally attempted, on the basis of
trial and error, until successful release of the jammed paper into one of
the infeed or output zones.
A drawback with this method is that the manually operable knob located
outside the printer housing rotates with the drive roller during normal
operation of the printer. Any accidental contact made with the knob will
disturb the line feeding of paper by the drive roller. This will result in
displacement of the paper during the sensitive printing processing.
Consequently, the printing quality will be affected, and particularly so
in high resolution printers.
In an alternative system, a shaft is arranged on an axis parallel with the
axis of the drive roller. The shaft supports a manually operable knob
which is located outside the housing of the printer. When the knob is
depressed in an axial direction of the shaft, a gear supported by the
shaft engages with a gear attached to the drive roller. A user wishing to
clear a paper jam simply pushes the exposed knob towards the body of the
printer to engage the drive roller gear train, and turns the knob at the
same time to direct the paper away from the drive roller. An advantage of
this improved system is that the knob is not rotating while the printer is
printing. Thus, accidental contact made with the knob is less likely to
disturb the line feeding of paper which occurred in the existing solution.
However, when using the alternative system there is still a considerable
risk that the knob will be accidentally pushed in, resulting in
disturbance of the line feeding of paper. This is especially so, since in
the unengaged position the knob is particularly exposed from the body of
the printer.
Furthermore, due to the ergonomics of the alternative system, a user
wishing to remove a paper jam will be required to perform repeated
"pushes" and "turns" of the knob. This problem has been addressed in known
systems by increasing the gear ratio of the gear train so that each turn
of the knob will cause increased rotation of the drive roller. However,
this fix solution is not ideal since fast turning of the knob will
generate undue stress to the gear train and drive motor. Additionally, the
frictional resistance of the system will increase so that turning of the
knob will be harder for a user.
In certain printers such as the DeskJet 1100C, available from the
Hewlett-Packard Company, USA, the pick roller is selectively coupled to
the drive roller via a gear and clutch arrangement. A short reverse
rotation of the drive roller causes the pick roller to engage with the
drive roller for one rotation of the pick roller in order to pick one
sheet of paper from the paper stack. Because during normal operation the
drive roller only performs forward rotations, the short reverse rotation
provides a convenient initiation of the sheet picking operation. However,
when removing paper jams using the aforementioned manual systems, the
drive roller will typically be reversed and further sheets will be picked
from the sheet stack. This is undesirable since the newly fed sheets may
compound the jamming problem by becoming jammed themselves. Moreover,
these extra sheets will be wasted.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a printer which has a
manually operable means for directing paper out of a jammed condition. The
manually operable means is preferably engaged when it is moved to a
retracted axial position. Therefore accidental disturbance of the printer
line feed by contact or depression of the manually operable means is
prevented.
According to a first aspect of the present invention there is provided a
printer having a facility for manually directing a printing medium along a
printing medium path, the printer comprising: an external housing; a drive
roller arranged about an axis of rotation for feeding a printing medium
through a processing zone of the printer; a control member arranged about
an axis of rotation, and movable between a first axial position in which
the control member protrudes from said external housing so as to be
manually actuable, and a second axial position in which the control member
is retracted relative to the first axial position; and a coupling
mechanism selectively coupling the control member and the feed roller to
translate rotational movement of the control member into rotational
movement of the feed roller, said coupling mechanism being engaged when
the control member is in the first axial position and disengaged when the
control member is in the second axial position.
A printer in accordance with the first aspect of the present invention has
an advantage that the coupling mechanism may only be engaged when the
control member is moved to the first axial position. Thus, mere accidental
contact with or depression of the control member when it is in the second
axial position will not cause the coupling mechanism to engage.
Consequently, there will be no disturbance of the printer's line feed when
the printer is printing.
Ideally, the control member is biased towards the second axial position.
This has the advantage that the control member will automatically return
to the axial position in which the coupling mechanism is disengaged. The
control member will only move to the first axial position when manually
guided there. Accordingly, accidental disturbance of the printer's line
feed is less likely to occur.
Suitably, the control member is substantially flush with the external
housing in the second axial position. Since in general the control member
is only required to be operated following a paper jam, having the control
member flush with the printer housing has an advantage in helping minimise
the dimensions of the printer. Furthermore, the control member is again
less likely to move to the engaged position except when it is
intentionally moved there manually.
The control member may comprise an axial shaft with a manually actuable
knob at a distal end thereof. Preferably, the knob includes a hinge
supporting a lever, which lever may be extended to aid movement of the
control member from the second axial position to the first axial position,
and to aid continuous manual rotation of the knob.
In a preferred embodiment, the printer further comprises: a picking
mechanism selectively coupled to the drive roller, for picking individual
sheets of media from a sheet media stack; and a linkage mechanism coupled
to the shaft of the control member, such that when the control member is
in the first axial position, the linkage mechanism engages with the
picking mechanism to disable picking of further individual sheets. The
linkage member may comprise a shaft arranged in parallel with the control
member shaft, and a pivotally mounted lever attached to both the control
member shaft and the linkage member shaft, the lever translating axial
movement of the control member shaft in one direction into axial movement
of the linkage mechanism shaft in an opposite direction, whereby movement
of the control member to the first axial position causes movement of the
linkage mechanism shaft in a direction so as to engage with the picking
mechanism to disable further picking of further individual sheets.
Suitably, the drive roller and the control member are arranged about
parallel axes of rotation. Furthermore, the coupling mechanism may
comprise a gear train having at least two gears which mesh with each other
when the control member is in the first axial position, such that a manual
angular displacement of the control member causes a proportional angular
displacement of the drive roller.
According to a second aspect of the present invention there is provided a
printer having a facility for manually directing a printing medium along a
printing medium path, the printer comprising: a drive roller arranged
about an axis of rotation for feeding a printing medium through a
processing zone of the printer; a control member comprising an axial shaft
with a manually actuable knob at a distal end thereof, the control member
arranged about an axis of rotation, and movable between a first axial
position and a second axial position; a coupling mechanism selectively
coupling the control member and the feed roller to translate rotational
movement of the control member into rotational movement of the feed
roller, the coupling mechanism being engaged when the control member is in
the first axial position and disengaged when the control member is in the
second axial position; a picking mechanism coupled to the drive roller,
for picking individual sheets of media from a sheet media stack; and a
linkage mechanism coupled to the shaft of the control member, such that
when the control member is in the first axial position, the linkage
mechanism engages with the picking mechanism to disable further picking of
sheets.
DESCRIPTION OF THE DRAWINGS
FIG. 1a is a schematic diagram of a prior art sheet feeding system, with
the picking roller and paper sheets in an initial state.
FIG. 1b is a schematic diagram similar to that of FIG. 1a, but with the
picking roller feeding the first (top) paper sheet into the infeed zone.
FIG. 1c is a schematic diagram similar to that of FIG. 1b, but with the
picking roller having fed the first paper sheet to the drive roller which
it turn is feeding the sheet into the processing zone.
FIG. 1d is a schematic diagram similar to that of FIG. 1c, but with the
picking roller having returned to its initial state and the first paper
sheet having become jammed beyond the drive roller.
FIG. 1e is a schematic diagram similar to that of FIG. 1d, but with the
picking roller feeding a second (top) paper sheet into the infeed zone and
the first paper sheet remaining jammed.
FIG. 2a is a side view of a prior art gear and clutch arrangement for
selectively coupling the drive roller to the pick roller, shown in the
decoupled state.
FIG. 2b is an isometric view of the gear and clutch arrangement of FIG. 2a.
FIG. 3a is a cross-sectional view of the gear and clutch arrangement of
FIG. 2a showing the clutch disengaged.
FIG. 3b is a cross-sectional similar to that of FIG. 3a, but from a reverse
angle.
FIG. 4a is side view of the gear and clutch arrangement of FIG. 2a, shown
in the coupled state.
FIG. 4b is isometric view of the gear and clutch arrangement of FIG. 2a,
also shown in the coupled state.
FIG. 5 is a cross-sectional view of the gear and clutch arrangement of FIG.
2a, showing the clutch engaged.
FIG. 6a is a perspective view of a control member and a linkage mechanism
in accordance with the invention, with the control member in the retracted
position.
FIG. 6b is a side view of the control member and linkage member of FIG. 6a,
with the control member shown flush with the external housing of the
printer.
FIG. 7a is a perspective view of the control member and linkage mechanism
of FIG. 6a, with the control mechanism in the extended position.
FIG. 7b is a side view of the control member and linkage mechanism of FIG.
7a, with the control member shown protruding from the external housing of
the printer.
FIG. 8a is a partial view of the external housing of the printer showing an
alternative control member in accordance with the invention in the
retracted position.
FIG. 8b is a cross-sectional view of FIG. 8a along line A--A, showing the
control member flush with the external housing of the printer.
FIG. 9a is a partial view similar to that of FIG. 8a, but with the control
member in the extended position.
FIG. 9b is a cross-sectional view of FIG. 9a along line A--A, showing the
control member protruding from the external housing of the printer.
FIG. 10a is a side view of the gear and clutch arrangement of FIG. 2a,
modified in accordance with the invention to include an engagable flange
portion.
FIG. 10b is an isometric view of the gear and clutch arrangement of FIG.
10a.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
As stated above, the present invention relates generally to feed systems of
the type used to advance sheet media along a path. Although the system is
described in the context of a single-sheet printer, those skilled will
appreciate that the system is similarly useful in a variety of sheet
processing machines, whether in a printing, faxing, copying or other
applications where it is desired to pass sheets along a sheet media path.
PAPER FEEDING AND JAMMING
In FIG. 1a, there is shown a simplified schematic drawing of a prior art
sheet feeding system 100 comprising, in accordance with the sequence of a
feeding operation, an input tray 110 containing a stack of paper sheets P,
a pick roller 120, a infeed zone sheet guide 130, a drive roller 140
co-operating with a pinch roller 150, and a processing zone sheet guide
160. Each roller 120, 140, 150 comprises an axially mounted shaft 122,
142, 152 supporting one or more roller members 124, 144, 154 respectively.
The shafts 122, 142, 152 are made, for example, from metal such as
stainless steel. In contrast, the roller members 124, 144, 154 are formed,
for example, from a rubber-like material which gives them a frictionally
adherent surface characteristic. The pick roller 120 includes three such
roller members 124, each having an annular shape with a asymmetrically
flattened external surface, whereas the drive and pinch roller 140, 150
each include a single roller member 144, 154 having a uniform annular
shape.
Standard operation and jamming of the sheet feeding system will now be
described with reference to FIGS. 1a, 1b, 1c, 1d, and 1e. Initially, the
flattened surfaces of the pick roller members face the stack of paper
sheets P as shown in FIG. 1a. Rotation of the pick roller members in a
clockwise direction causes the leading edge of the curved surface to
frictionally contact the top surface of the stack of paper sheets P.
Continued rotation of the pick roller causes the first sheet A to be fed
into the infeed zone. Here it is guided by the infeed zone guide 130
towards the drive and pinch rollers, as illustrated in FIG. 1b. As the
trailing edge of the curved surface of each pick roller member rises from
the paper surface, the top sheet A will be caught by the pinching action
of the drive and pinch rollers. The pinch action results from the drive
roller rotating in a clockwise direction against the pinch roller which
rotates in an anti-clockwise direction, as illustrated in FIG. 1c. The top
sheet is then fed by the drive and pinch rollers, with guidance from the
processing zone paper guide, into processing zone of the printer.
The paper may be stopped by some obstruction in the paper path. Continued
feeding of the paper by the drive and pinch rollers will then result in
the paper building up behind the obstruction and causing a paper jam, as
illustrated in FIG. 1d. The pick roller may then be activated to pick
another sheet. This second sheet will be fed by the pick roller towards
the infeed zone with the first sheet remaining in the jammed state, as
illustrated in FIG. 1e.
In addition to the illustrated elements, the sheet feeding system also
comprises a gear train which permanently couples the drive roller to a
drive motor to provide automated control of the sheet feeding system. The
pinch roller is mounted so as to be freely rotational. The pinch roller is
also biased against the drive roller so that the contact surfaces of the
two rollers co-operate, forcing the pinch roller to rotate in an opposite
sense to the rotation of the drive roller. The pick roller forms part of a
picking mechanism which selectively couples to the drive roller so that
the sheet picking operation can be selectively activated. One such picking
mechanism is the prior art reverse picking mechanism referred to in the
introduction.
REVERSE PICKING MECHANISM
The reverse picking mechanism used in the Hewlett-Packard DeskJet 1100C
sheet feed printer will now be described with reference to FIGS. 2a, 2b,
3a, 3b, 4a, 4b, and 4c.
In FIGS. 2a and 2b, there is shown a gear and clutch arrangement 200 viewed
from an opposite direction to the side view of FIG. 1a. The arrangement
200 comprises a set of gear wheels 210, 220, 230, 232, and 234 arranged on
parallel axes and linked in series with each other. The gear wheel 210
rotates about a fixed axis and is coupled indirectly to the drive shaft
142 of the drive roller 140. Rotation of the drive roller 140 is
translated via a gear train into opposite rotation of the gear wheel 210.
The gear wheel 220 is freely mounted for independent rotation on the pick
shaft 122. The pick shaft 122 is shown in cross-section in FIG. 2a, and
defines the axis P-P in FIG. 2b. The gear wheel 230 rotates about a fixed
axis and is directly coupled to the gear wheel 220 and the gear wheel 232.
The arrangement further comprises a clutch member 240 and an activating
lever 250. The clutch member is mounted for rotation about a movable axis
defined by the finger portion 242, as will be described in further detail.
The activating lever 250 and the gear wheel 232 are mounted on a common
fixed axis and are independently rotatable. The gear wheel 234 is mounted
for rotation about a movable axis associated with an arm of the activating
lever 250. The rotational mounting is of the frictional type which
resists, but does not prevent, rotation of the gear wheel 234.
The gear and clutch arrangement is shown in FIGS. 2a and 2b in the
disengaged or declutched state. This corresponds to the picking mechanism
not being activated, as illustrated originally in FIGS. 1a and 1d.
Further reference is now made to FIGS. 3a and 3b, which show in greater
detail the clutch of the gear and clutch arrangement 200. FIG. 3a is a
cross-sectional view of the clutch of FIG. 2b in the direction of arrows
R, whereas FIG. 3b is a cross-sectional view of the clutch of FIG. 2b in
the direction of the arrow S. FIG. 3b shows in addition a clutch support
260 of the gear and clutch arrangement 200 which is fixedly mounted to the
pick shaft 122. The clutch support 260 has an aperture which receives the
finger portion 242 of the clutch member 240, allowing the clutch member to
rotate about the central axis of the finger portion 242. FIG. 3a shows the
clutch member 240 with a hollowed out interior, and a portion of the gear
wheel 220 freely mounted on the pick shaft 122 for rotation within the
clutch member interior.
In the declutched state, a catch portion 254 of the activating lever 250 is
engaged with a barb portion 246 of the clutch member 240. A spring 270
connected between a peg 262 on the clutch support and a peg 244 on the
clutch member 240 biases the barb portion 246 against the catch portion
254.
To activate or initiate the picking mechanism, the printer instructs the
drive motor to briefly rotate the drive roller in the reverse feed
direction (anti-clockwise in FIGS. 1a and 1d). This causes the gear wheels
210, 230, and 234 to rotate in the anti-clockwise direction (in FIGS. 2a
and 2b), and the gear wheels 220 and 232 to rotate in the clockwise
direction. The frictional mounting of the gear wheel 234 generates a
anti-clockwise drag torque opposing the clockwise motion of the wheel. The
torque is translated to the lever 232 and urges the lever in the direction
of arrow T. The torque is sufficient to overcome the force of the spring
270 to release the catch portion 254 from the barb 246. The gear and
clutch mechanism is now in the engaged or clutched state, as shown in
FIGS. 4a, 4b and 5.
As shown in FIGS. 3a and 3b, release of the catch portion 254 from the barb
246 causes the clutch member to rotate under the force of the spring 270
about the finger portion 242. The direction of motion is indicated by the
arrow C. After rotation, the clutch member becomes seated in the clutched
position shown in FIG. 5. In this position, an inwardly directed tooth
portion 248 of the clutch member 240 abuts one of two diametrically
opposed shoulder portions 222 of the gear wheel 220.
Once the reverse motion of the drive roller has clutched the picking
mechanism, the printer instructs the drive motor to rotate the drive
roller in the forward direction (clockwise in FIGS. 1a and 1d). This
causes the gear wheels 210, 230, and 234 to rotate in the clockwise
direction (in FIGS. 4a and 4b), and the gear wheels 220 and 232 to rotate
in the anti-clockwise direction. The frictional mounting of the gear wheel
234 now generates a clockwise drag torque opposing the anti-clockwise
motion of the wheel. The torque is translated to the lever 232 and urges
the lever back in the direction 20 of arrow T' until the catch portion
rests against the outer surface of the barb portion.
Meanwhile, rotation of the gear wheel 220 (clockwise in FIG. 5) forces the
shoulder portion 222 against the tooth portion 248 of the clutch member
240. The clutch member in turn forces the clutch support via the finger
portion 242, which in turn forces the shaft 122. Thus, rotation of the
gear wheel 220 causes corresponding rotation of the shaft 122 and the pick
roller members to pick a single sheet from the sheet stack.
During rotation of the clutch member, the catch portion of the lever 250 is
cammed against the outer surface of the clutch member. After almost one
rotation of the clutch member, the barb portion of the clutch member
catches on the catch portion of the lever 250. Continued rotation of the
gear wheel 220 forces the clutch member and the barb portion against the
catch portion, lifting the clutch member out of the clutched state. Thus,
having completed a single sheet pick, the gear and clutch arrangement once
more returns to the declutched state, as shown in FIGS. 2a, 2b, 3a and 3b.
CONTROL MEMBER AND COUPLING MECHANISM
Sometimes, it may be desirable to feed paper by means of the drive roller
without having to operate the printer drive motor. Such times may include
when paper is jammed in the printer as shown in FIGS. 1d and 1e, or when
the drive motor fails. The following describes a system for enabling
feeding of paper manually in accordance with the invention.
In FIGS. 6a, 6b, 7a and 7b, there is shown a control member and part of a
coupling mechanism. The control member comprises a knob 610 attached to a
shaft 620. The shaft is mounted to allow rotation of the control member
about an axis as indicated by the arrow R in FIG. 7a. The shaft mounting
also allows axial movement of the control member between the position
shown in FIGS. 6a and 6b, and the position shown in FIGS. 7a and 7b. The
shaft is also mounted so that it is biased towards the position shown in
FIGS. 6a and 6b. This can be implemented in various known ways, for
example, by means of a spring or an elastic band arrangement.
The coupling mechanism comprises a first gear wheel 710 located on the
shaft 620 of the control member, and a second gear wheel 720 indirectly
coupled via a gear train to the drive roller.
The control member is shown in FIGS. 6a and 6b in the disengaged axial
position. In this position there is no interaction between the first gear
wheel 710 and the second gear wheel 720 of the coupling mechanism. The
coupling mechanism is therefore disengaged. Any rotation of the knob 610
will not feed any paper present in the paper feed path.
In FIGS. 7a and 7b, the control member is shown in the engaged axial
position. In this position the first gear wheel 710 meshes with the second
gear wheel 720 of the coupling mechanism. The coupling mechanism is
therefore engaged. Manual rotation of the knob by a user will direct paper
adjacent the drive roller towards either the infeed zone or the output
zone. To assist a user in continually rotating the control member, the
knob 610 includes a lever 630 attached at a proximal end to a hinge in the
knob. The lever may be extended and grasped at a distal end to rotate the
knob 610. FIG. 7a and 7b shows the lever extended with the distal end
having a independently rotatable portion to further assist manual
rotation.
In FIGS. 6b and 7b, the relative position of the printer housing and the
knob 610 of the control member is shown for the disengaged and engaged
states respectively. In the disengaged state, the knob is flush with the
external housing of the printer so that the external dimensions of the
printer are minimised. In the engaged state, the knob 610 and the lever
630 protrude from the printer housing increasing the printers external
dimensions. Because the engaged state is only used occasionally, the
default state of the systems provides the manually operable knob flush
with the printer housing. The knob is therefore less likely to be damaged
during normal operation. Biasing of the control member to the disengaged
state also has a number of benefits. For example, the biasing will
automatically return the control member to the disengaged position after
manual engagement. Also, the control member will be less likely to engage
unless engagement is manually intended.
In FIGS. 8a, 8b, 9a and 9b, there is shown an alternative knob of the
control member. In this embodiment, movement of the lever from the
retracted position shown in FIG. 8a to the extended position shown in FIG.
9a forces the control member to the engaged position. The force is
produced by the proximal end of the lever urging against the edge of the
printer housing. To operate in the extended position, a user rotates the
distal end of the lever whilst at the same time pressing the lever against
the printer housing to maintain engagement. Once operation is complete, a
user can let go of the lever. The return biasing of the control member to
the disengaged position will flick the lever back to the flush retracted
position shown in FIG. 8a.
LINKAGE MECHANISM
If jammed paper needs to be removed from the sheet feed path such as in the
situation shown in FIGS. 1d and 1e, it is desirable to prevent further
sheets being picked and fed. The following describes a system in
accordance with the invention for disabling the reverse picking mechanism.
Referring back to the embodiment of FIGS. 7a, 7b, 8a, and 8b, there is
shown a linkage mechanism comprising a lever 810 and a shaft 820. The
lever 810 is pivotally mounted at its centre, and is connected at one end
to the shaft 620 of the control member, and at the other end to the shaft
810 of the linkage mechanism. The lever couples the two shafts so that
axial movement of one shaft produces corresponding axial movement of the
other shaft in the opposite direction. FIGS. 7a, 7b, 8a, and 8b also show
the lever 250' of the gear and clutch mechanism modified in accordance
with the invention. This lever is shown in more detail in FIGS. 10a and
10b, and includes an additional flange portion 256 for interacting with
the shaft linkage mechanism.
When the control member is in the disengaged position, as shown in FIGS. 6a
and 6b, there is no interaction between the shaft of the linkage mechanism
and the lever of the picking mechanism. Consequently, operation of the
printer feeding system including sheet picking may proceed as normal.
When the control member is moved to the engaged position, the lever of the
linkage mechanism acts to translate axial movement of the shaft 620 into
opposite axial movement of the shaft 820. Once the coupling mechanism is
engaged, the shaft 820 will have moved to the position shown in FIGS. 7a,
7b, 10a and 10b, in which it interacts or engages with the lever of the
picking mechanism.
In one situation, the control member may be moved to the engaged position
in order to remove a paper jam such as the type shown in FIG. 1d. In this
case, the gear and clutch mechanism will be in the declutched state.
Engagement of the picking mechanism lever will have the effect of
maintaining the gear and clutch mechanism in the declutched state. Reverse
manual driving of the drive roller will not therefore result in any
further sheets being picked from the sheet stack. Consequently, the
reverse picking mechanism will be temporarily disabled.
In another situation, the control member may be moved to the engaged
position in order to remove a paper jam such as the type shown in FIG. 1e.
In this case, the gear and clutch mechanism will be in the clutched state.
Engagement of the picking mechanism lever will have the effect of urging
the lever against the outer surface of the gear and clutch mechanism. The
partially picked sheet will continue to be fed dependent on the manual
driving until the clutch member is caught by the catch of the lever. The
picking mechanism will then declutch and will remain declutched as long as
the control member is engaged. Consequently, reverse manual driving of the
drive roller will again not result in any further sheets being picked from
the sheet stack.
Top